<?php 
$options = array(
	"Nhóm 1"	=>	array(
		"xin chao",
		"xin chao 1",
		"xin chao 2",
		"xin chao 3"
	),
	"Nhóm 2"	=>	array(
		"xin chao 4",
		"xin chao 5",
		"xin chao 6",
		"xin chao 7",
		"xin chao 8"
	),
	"Nhóm 3"	=>	array(
		"xin chao 9",
		"xin chao 10",
		"xin chao 11",
		"xin chao 12"
	)
);
echo $form->create('asdfasf');
echo $form->input('abc', array('options' => $options));
echo $form->end();
?>